Continuous-casting mold with refractory top liner



United States atent Richard S. Crowell Flossmoor. lllinois [72] Inventor {21] App1..\o. 692,776 [22} Filed Dec. 22. 1967 [73} Assignee United States Steel Corporation a corporation of Delaware [54] CGXTINUOLS-CASTING MOLD WITH REFRACTORY TOP LINER 6 Claims, 3 Drawing Figs.

[52] L15. Cl 164/273, 164/259.164/268.164/338 [51] lnt.Cl v ..B22d11/l0 Field ofSeareh 164/66. 73.

[56] References Cited UNITED STATES PATENTS 3.354.935 11/1967 Mann' 16-1/82X 3.446267 5/1969 Gricol et al. 164/278 3.234.608 2/1966 Peras 164/52 FOREIGN PATENTS 1.160.289 2/1958 France 164/82 891,444 9/1953 Germany r r 164/281 688.955 3/1953 Great Britain. 164/281 947.626 1/1964 Great Britain... 164/281 1.026.399 4/1966 Great Britain 164/82 Primary Examiner l. Spencer Overholser Assistant Examiner-R Spencer Annear Attorney- Walter P. Wood ABSTRACT: A tubular. flow-through. water-cooled mold has a refractory collar detachably mounted on top thereof with an internal flange extending into the mold cavity but spaced slightly from the mold wall. lnert gas is maintained under pressure in the space between the depending inner flange and the mold wall to prevent molten metal from rising therebetween. The flange has an electrical resistance heater embedded therein. The collar has a spout permitting slag accumulations floating on the molten metal to be drained off.

INVENTOR RICHARD S. CROWELL I H I I I I I I I I I I I I I I II I l I I l l l I l I l l I l I II I Patented Get. 13, 1970 MEVSMWMQQ QM q QQQKEQQ 1' CONTINUOUS-CASTING MOLD WITH REFRACTORY TOP LINER BACKGROUND OF THE INVENTION This invention relates to continuous casting and. in particular, to a mold of the tubular flow-through type surmounted by a refractory collar, effective to keep molten metal therein from freezing.

In casting continuously into flow through molds as known heretofore, scum or slag accumulations on the surface of the molten metal have become embedded in the skin formed in contact with the mold walls. The embedded scum constitutes an area of weakness in the skin which is liable to breakout after leaving the mold. Even if no breakout occurs, the scum is a surface imperfection which must be removed by scarfing.

BRIEF SUMMARY OF THE INVENTION l have invented an improved mold by which the foregoing difficulty is obviated. In a preferred embodiment, I add to the top of a conventional mold a refractory collar having an internal flange depending within the mold cavity adjacent the mold BRIEF DESCRIPTION OF THE DRAWINGS A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawings:

FIG. 1 is a plan view;

FIG. 2 is an elevation; and 7 FIG. 3 is a transverse sectional view on the plane of line III-III of FIG. 1, with parts in elevation.

DETAILED DESCRIPTION OI THE PREFERRED EMBODIMENT Referring now in detail to the drawings, a conventional tubular, flow-through, water-cooled mold is indicated at 10. A refractory collar 11 is disposed on top of mold 10. It has an internal flange 12 depending into the mold cavity 13 and an external angle-iron frame 14. It is held on the mold by clamp bolts 15 pivoted thereto, whichcooperate with slotted lugs 16 extending outwardly from' the sides and ends of the frame 14. A drain spout 17 is formed in one end of collar 11. Flange 12 has an electrical resistance heating conductor 18 embedded therein from the ends of which terminals 19 are brought out for connection to a suitable current supply.

As shown in FIG. 3, the outer surface of flange 12 is spaced inwardly of the inner surface of the wall of mold 10, leaving a space 20. A sealing gasket 21 is disposed between the bottom of collar 11 and the top of mold 10. A series of gas passages 22 are supplied with inert gas such as nitrogen, under suitable pressure, as by a manifold (not shown). The gas pressure is maintained at such value that. when the mold 10 has been filled with molten metal and the level thereof has risen nearly to the top of collar 11. rise of metal in space 20 will be prevented. The gas pressure may be controlled by suitable means such as one or more thermocouples 23 embedded in the wall of mold I0, and conventional control equipment responsive thereto, so the pressure will be increased if the metal rises above a certain level in space 20. Oil for lubricating mold {0 may be supplied through passages 24 and will also aid in contributing positive pressure to the space 20.

In starting up with my improved mold, the collar is preheated by heater 18, so molten metal rising therein after mold I0 has been filled will not be chilled or frozen. Thus metal at a level above the bottom offlange 12 is kept molten and freezing occurs only at a level therebelow where cast metal comes in contact with the wall of mold I0. Scum collecting on the surface of the metal within collar 11 may be periodically drained off through spout l7.

Collar 11 may be of any suitable refractory such as alumina. Heating conductor 18 may be of graphite. Terminals 19, of course, are of copper.

It will be evident from the foregoing that my invention prevents scum from becoming embedded in the surfaces of the casting as it freezes and permits scum to be removed before the liquid metal reaches the level in mold 10 at which formation of the skin of the casting begins.

Although I have disclosed herein the preferred practice of my invention, I intend to cover as well any change or modification therein which may be made without departing from the spirit and scope of the invention as set forth in the claims.

I claim:

I. The combination, with a tubular flow-through mold adapted to receive a stream of molten metal, of a device for collecting slag which accompanies the metal and thus preventing the slag from becoming embedded in the surface of a casting formed in said mold, said device comprising a refractory collar mounted on the top of said mold and having a flange around its bottom depending into the mold cavity, said flange being dimensioned to leave a space between its outer surface and the inner surface of the mold wall, means communicating with said space for introducing gas under pressure thereto to prevent molten metal in the mold from rising into said space, the top of said collar being open, and means at the top of said collar for draining collected slag away from the mold.

2. The combination as defined in claim 1, characterized by an electrical heating conductor embedded in said flange.

3. The combination defined by claim 1, characterized by said collar conforming to the shape of the mold cavity and having an angle-iron frame thereon.

4. The combination defined by claim 3, characterized by detachable clamp means on said mold adapted to engage said frame.

5. A combination as defined in claim 1 further .comprising 

